1. Field of the Invention
The present invention relates to a backlight module and particularly to a backlight module without a light guiding plate and a diffusing plate and using light-emitting diodes (LEDs) as a light source.
2. Description of the Prior Art
Conventionally, a cold cathode fluorescent lamp (CCFL) is generally used as a light source in a liquid crystal display (LCD). However, such CCFL may not have a good color saturation obtained as compared to light-emitting diodes (LEDs) when used as the light source in the LCD.
Since the LCD is provided not only for replacement of other displays but also for the environmental protection reason, it is anticipated that the CCFL containing mercury would possibly be phased out in the future. In this regard, the light-emitting diodes can be a better choice as being a light source for the LCD.
Referring to FIG. 1, a conventional backlight module of LCD without a light guiding plate is schematically shown therein. When using LEDs 110 as a light source, the backlight module 100 further comprises an optical diverting mechanism 120 for guiding a light emitted from the LEDs 110 to a bottom reflector 130 so that the light may be efficiently guided out of the backlight module through a reflector and a diffusing plate 140 therein. However, the light from the LEDs 110 generally suffers a considerable energy loss after passing through the optical diverting mechanism 120, the bottom reflector 130, the reflector, and the diffusing plate 140 in the backlight module without a light guiding plate and thus luminance presented to a user by the light source 110 is not sufficient. For this reason, high power LEDs are required. However, this may otherwise increase cost of the backlight module 100 and thus the overall LCD.
In view of the above shortcomings, it is a critical issue regarding how to achieve a backlight module having a reduced luminance loss.